According to a not-for-profit anti-spam organization, a Dutch web hosting company has caused disruption and the global slowdown of the internet. This attack was potent because it exploited the 'domain name system' which is used every time a web address is entered into a computer.

A Dutch web-hosting company caused disruption and the global slowdown of the internet, according to a not-for-profit anti-spam organization.

The interruptions came after Spamhaus, a spam-fighting group based in Geneva, temporarily added the Dutch firm, CyberBunker, to a blacklist that is used by e-mail providers to weed out spam.

Cyberbunker is housed in a five-story former NATO bunker and famously offers its services to any website “except child porn and anything related to terrorism". As such it has often been linked to behaviour that anti-spam blacklist compilers have condemend.

It retaliated with a huge 'denial of service attack'. These work by trying to make a network unavailable to its intended users,overloading a server with coordinated requests to access it. At one point, 300 billion bits per second were being sent by a network of computers, making this the biggest attack ever.

The attack was particularly potent because it exploited the 'domain name system', which acts like the telephone directory of the internet and are used every time a web address is entered into a computer.

Patrick Gilmore, of digital content provider Akamai Networks told the New York Times that Cyberbunker did not believe spamming users was wrong. “These guys are just mad. To be frank, they got caught," he alleged. "They think they should be allowed to spam.”

Calling the disruptions “one of the largest computer attacks on the Internet,” the New York Times reported today that millions of ordinary web users have experienced delays in services such as Netflix video-streaming service or couldn’t reach a certain website for a short time.

“The size of the attack hurt some very large networks and internet exchange points such as the London Internet Exchange,” John Reid, a spokesman for Spamhaus, said in an e-mailed response to questions by Bloomberg News. “It could be thousands, it could be millions. Due to our global infrastructure, the attackers target places all over the world.”

Spamhaus was targeted with a so-called distributed denial of service attack on the evening of March 15, Reid said.

“The only thing we would like to say is that we do not, and never have, sent any spam,” Cyberbunker spokesman Jordan Robson said in an e-mail.

Sven Olaf Kamphuis, an internet activist who told the New York Times he was a spokesman for the attackers, said that Cyberbunker was retaliating against Spamhaus for “abusing their influence” as the gatekeeper of lists of spammers. “Nobody ever deputized Spamhaus to determine what goes and does not go on the Internet,” he claimed. “They worked themselves into that position by pretending to fight spam.”

Such attacks are growing in quantity as well as scale, according to Vitaly Kamluk, chief malware expert of Kaspersky Lab’s global research and analysis team. The two main motives for the disruptions are money through cybercrime and political and social activism, he said.

“This is indeed the largest known DDoS operation,” Kamluk said by e-mail. “Such DDoS attack may affect regular users as well, with network slowdown or total unavailability of certain web resources as typical symptoms.”

Cyberbunker claims that it has resisted a number of 'attacks' by Dutch police attempting to make arrests.